Filmes ultrafinos luminescentes de Acetato de Celulose com complexos de íons Eu3+ E Tb3+ obtidos por Langmuir-Blodgett
Data
2022-06-20
Autores
Figueiredo, Mayara Macedo 
Orientadores
Molina, Celso
Tipo
Trabalho de conclusão de curso
Título da Revista
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Resumo
A técnica de Langmuir-Blodgett (LB) permite a obtenção de filmes ultrafinos, organizados na forma de mono ou multicamadas a partir da transferência para suportes sólidos de monocamadas de anfifílicos organizados na interface ar-água, com potencial para várias aplicações tais como sondas luminescentes para bioaplicações e camadas ativas em dispositivos emissores de luz. Visando a obtenção de filmes com viés sustentável, foi utilizado neste trabalho um polímero derivado de fonte renovável (acetato de celulose) e que possua alta transparência na região do visível, juntamente com fosfolipídio ácido dimiristoilfosfatídico (DMPA), anfifílico insolúvel em água e formador de filmes de Langmuir. Foram também incorporados os complexos luminescentes Eu(tta)3(H2O)2 e Tb(acac)3(H2O)3. Assim, estudou-se o efeito da incorporação dos complexos, à monocamada mista formada por acetato de celulose e DMPA na interface ar-água. Os filmes de Langmuir foram caracterizados por isotermas de pressão e potencial superficial-área, microscopia no ângulo de Brewster e espectroscopia de absorção-reflexão no infravermelho para investigação das propriedades termodinâmicas, elétricas, morfológicas e estruturais das monocamadas. Os filmes são mais estáveis quando os componentes acetato de celulose e DMPA são misturados previamente e coespalhados na interface ar-água. As monocamadas foram comprimidas lateralmente e transferidas para suportes sólidos pela técnica LB e caracterizados por espectroscopia no infravermelho e de fotoluminescência. Os filmes LB apresentaram luminescência e apresentaram as principais emissões características dos íons Eu3+ e Tb3+ quando excitados via efeito antena. Além disso, parâmetros como tempo de vida do estado excitado foram obtidos, viabilizando os filmes como possível camada ativa para dispositivos emissores de luz.
The Langmuir - Blodgett (LB) technique allows obtaining ultrathin films, organized as mono or multilayers, from the transfer of monolayers of amphiphiles organized at the air-water interface to solid supports, with potential for several applications such as luminescent probes for bioapplications and active layers in light-emitting devices. Aiming at obtaining films with sustainable bias, a polymer derived from a renewable source (cellulose acetate), and which has high transparency in the visible region, was used in this work, together with a phospholipid dimyristoylphosphatidic acid (DMPA), an amphiphilic insoluble in water and able to form stable Langmuir films. The luminescent complexes Eu(tta)3(H2O)2 and Tb(acac)3(H2O)3 were also incorporated. Thus, the effect of incorporating the complexes into the mixed monolayer formed by cellulose acetate and DMPA at the air-water interface was studied. The Langmuir films were characterized by surface pressure and surface potential-area isotherms, Brewster angle microscopy, and infrared absorption-reflection spectroscopy to investigate the monolayers' thermodynamic, electrical, morphological, and structural properties. The films are more stable when the cellulose acetate and DMPA components are premixed and co-spread at the air-water interface. The monolayers were laterally compressed and transferred to solid supports by the LB technique and characterized by infrared and photoluminescence spectroscopy. The LB films showed luminescence and presented the primary characteristic emissions of Eu3+ and Tb3+ ions when excited via the antenna effect. In addition, parameters such as excited-state lifetime were obtained, enabling the films as possible active layer for light emitting devices.
The Langmuir - Blodgett (LB) technique allows obtaining ultrathin films, organized as mono or multilayers, from the transfer of monolayers of amphiphiles organized at the air-water interface to solid supports, with potential for several applications such as luminescent probes for bioapplications and active layers in light-emitting devices. Aiming at obtaining films with sustainable bias, a polymer derived from a renewable source (cellulose acetate), and which has high transparency in the visible region, was used in this work, together with a phospholipid dimyristoylphosphatidic acid (DMPA), an amphiphilic insoluble in water and able to form stable Langmuir films. The luminescent complexes Eu(tta)3(H2O)2 and Tb(acac)3(H2O)3 were also incorporated. Thus, the effect of incorporating the complexes into the mixed monolayer formed by cellulose acetate and DMPA at the air-water interface was studied. The Langmuir films were characterized by surface pressure and surface potential-area isotherms, Brewster angle microscopy, and infrared absorption-reflection spectroscopy to investigate the monolayers' thermodynamic, electrical, morphological, and structural properties. The films are more stable when the cellulose acetate and DMPA components are premixed and co-spread at the air-water interface. The monolayers were laterally compressed and transferred to solid supports by the LB technique and characterized by infrared and photoluminescence spectroscopy. The LB films showed luminescence and presented the primary characteristic emissions of Eu3+ and Tb3+ ions when excited via the antenna effect. In addition, parameters such as excited-state lifetime were obtained, enabling the films as possible active layer for light emitting devices.
Descrição
Citação
FIGUEIREDO, M.M. Filmes ultrafinos luminescentes de Acetato de Celulose com complexos de íons Eu3+ e Tb3+ obtidos por Lagmuir-Blodgett. 2022. 65 f. Trabalho de conclusão de curso (Graduação em Química) - Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, 2022.